Voltage-Gated Nanofluidic Synapse with Cation−π Interactions Enabled Ultra-Long-Term Memory

Voltage- and ligand-gated ion channels are crucial for neural information transmission and processing, inspiring ionic emulation via ion dynamics. Here, we report a voltage-gated nanofluidic synapse based on atomic-scale graphene channels that exhibit both short- and long-term plasticity. Short-term plasticity originates from transient ionic adsorption at the channel entrance. Long-term plasticity for potentiation and depression shows exceptional durability, with ∼50% synaptic enhancement and ∼40% suppression persisting beyond 5 h without noticeable decay, respectively, indicating ultra-long-term memory. Energy dispersive spectroscopy (EDS) reveals that the nonvolatile ionic memory is attributed to the persistent retention of deeply inserted potassium ions within graphene channels due to cation-π interactions. The device also demonstrates other essential synaptic functions, including paired-pulse facilitation (PPF) and depression (PPD) as well as spike-timing-dependent plasticity (STDP). Logic operations (AND/OR gates) are implemented by using multiple devices. The development of multifunctional graphene nanofluidic synapses benefits ionic neuromorphic computing.